1. Field of the Invention
This invention relates to a fire detector, the body of which is attached to a base thereof. Further, this invention relates to a device for detaching the body of a fire detector therefrom. More particularly, this invention relates to a locking structure for locking the body of a fire detector to the base thereof, which can be selectively locked thereto according to specifications thereof and can not be easily released therefrom by any person other than persons concerned but can be easily released therefrom by a person concerned. Moreover, this invention relates to a device for releasing the body of a fire detector, which is locked to the base thereof through such a locking structure.
2. Description of the Related Art
Generally, a fire detector is composed of a base and a body thereof. The base of the detector is fixed to the ceiling of a room with screws or the like. Further, the body of the detector is detachably mounted to this base with metal fitting parts. Meanwhile, in the case of a fire detector having such a configuration, the body thereof can be detached from the base thereof. Thus, the body thereof is sometimes stolen. Moreover, in the case of an ionization smoke detector, a radiation source is provided therein. Thus, if the body thereof is detached therefrom, radiation leakage may put a human body in danger. Therefore, the body of the fire detector is locked to the base thereof by securing the body to the base with screws or by forming the body and the base separately from each other and further engaging the base with the base, with the intention of preventing the body from being stolen, or of preventing a human body from being put into danger.
Hereinafter, conventional structures each for locking the body of a fire detector to the base thereof as disclosed in the Japanese Utility Model Public Disclosure Nos. 143690/1990 and 41393/1991 Official Gazettes will be described.
For example, the Japanese Utility Model Public Disclosure No. 143690/1990 Official Gazette discloses a locking structure for locking the body of a fire detector to the base thereof, in which an engaging projection 101 of a movable engaging portion 103 is fitted into a notched recess portion 102 as illustrated in the prior art FIGS. 10 and 11, so that the body and the base get into a locked state. Moreover, the Japanese Utility Model Public Disclosure No. 41393/1991 Official Gazette discloses a similar locking structure for locking the body of a fire detector to the base thereof.
Thus, in the case of the conventional fire detector, the body of the detector is locked to the base thereof by securing the body to the base with screws or by forming engaging members in the body and the base thereof. Conversely, in some cases, for instance, in case where the public peace is maintained at the installation location of the fire detector, the fire detector does not require such a locking structure. However, in this case, there is caused a problem that fire detectors each having the locking structure should be designed and manufactured in specifications, aside from fire detectors which do not require the locking structures, and thus the price of the manufactured detector becomes high.
Further, even in the case of the fire detector having the locking structure disclosed in the Japanese Utility Model Public Disclosure No. 143690/1990 and so on, situations in which the locking structure is not required by the detector are ignored. Therefore, the specifications concerning such a locking can not be freely altered. Especially, there is a case where the fire detector is installed by changing only a part of the specifications concerning the body thereof but without changing those concerning the base thereof. Thus, the aforementioned locking structure has a problem in that such a locking structure can not be changed into a non-locking structure. Moreover, the aforementioned locking structure is provided in an outer portion of the peripheral part of the body of the detector, as illustrated in FIG. 10. As a result, the locking structure can be easily unlocked from the outside of the detector. Consequently, the conventional fire detector has a problem in that such a locking structure is ineffective in preventing a theft.
Additionally, the conventional fire detector has another problem in that if the locked fire detector is mounted on a high ceiling, it is difficult for a person concerned to remove the body of the detector from the base thereof. The present invention is accomplished to resolve the problems of the conventional fire detector.